The present invention relates to a magnetic head for writing and reading data out of a magnetic recording medium as well as for erasing the data on the medium and, more particularly, to a magnetic head for use in a disk drive which uses a floppy disk or disket as a recording medium.
In parallel with the increase in the capacity of a disk drive, there is an increasing demand for diskets having great coercive forces, i.e., high densities. The current trend in the disk drive art is, therefore, toward diskets having smaller track widths. An erasure-precedent type magnet head is a recent achievement that implements a sufficient overwriting characteristic in relation to such a disket. For this type of magnetic head, a reference may be made to Toshiba Review, Vol. 43, No. 11, page 887.
The erasure-precedent type magnetic head has a pair of sliders for causing a disket to slide. An erase core is held between the sliders such that it extends in parallel to a track of a disket. The erase core has an erase gap extending perpendicular to the track in close proximity to one end thereof. A read/write core is held between the sliders in the same positional relation to the track as the erase core. A read/write gap is formed in the vicinity of one end of the read/write core and, like the erase gap, extends perpendicular to the track. When the head is in a write mode, the erase gap effects DC erasure on the track while the read/write gap writes data in the so erased track.
A prerequisite with the above-described type of magnetic head is that the distance between the erase gap and the read/write gap be reduced to reduce the track width as stated above. Specifically, it is necessary to locate the gaps of the individual cores in close proximity to each other at opposite sides of the position where the cores are connected to each other. This brings about a problem that each core cannot achieve a sufficient magnetic path since part thereof exists between the two gaps. During a read mode operation, the erase gap picks up data or flux from a track of interest before the read/write gap picks it up, resulting in the flux leaking to the read/write head as noise. The noise is propagated to the magnetic circuit of the read/write gap to critically lower the S/N ratio of signals read out. To reduce crosstalk ascribable to the erase gap, a shield may be used to prevent the noise from reaching the read/write core. In practice, however, providing such a shield is not easy and would not offer a satisfactory result. While the erase gap may be provided with an azimuth, as disclosed in Japanese Patent Laid-Open Publication No. 192004/1989 by way of example, this kind of scheme would need a complicated structure and a great number of difficult fabricating steps.